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OpenCloudOS-Kernel
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io_uring: pin SQPOLL data before unlocking ring lock 

We need to re-check sqd->thread after we've dropped the lock. Pin
the sqd before doing the lockdep lock dance, and check if the thread
is alive after that. It's either NULL or alive, as the SQPOLL thread
cannot exit without holding the same sqd->lock.

Reported-and-tested-by: syzbot+337de45f13a4fd54d708@syzkaller.appspotmail.com
Fixes: fa84693b3c ("io_uring: ensure IORING_REGISTER_IOWQ_MAX_WORKERS works with SQPOLL")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2021-09-13 13:08:51 -06:00
parent dd47c10453
commit 41d3a6bd1d
1 changed files with 9 additions and 3 deletions
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12
fs/io_uring.c
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@ -10563,10 +10563,12 @@ static int io_register_iowq_max_workers(struct io_ring_ctx *ctx,
* ordering. Fine to drop uring_lock here, we hold
* a ref to the ctx.
*/
refcount_inc(&sqd->refs);
mutex_unlock(&ctx->uring_lock);
mutex_lock(&sqd->lock);
mutex_lock(&ctx->uring_lock);
tctx = sqd->thread->io_uring;
if (sqd->thread)
tctx = sqd->thread->io_uring;
}
} else {
tctx = current->io_uring;
@ -10580,16 +10582,20 @@ static int io_register_iowq_max_workers(struct io_ring_ctx *ctx,
if (ret)
goto err;
if (sqd)
if (sqd) {
mutex_unlock(&sqd->lock);
io_put_sq_data(sqd);
}
if (copy_to_user(arg, new_count, sizeof(new_count)))
return -EFAULT;
return 0;
err:
if (sqd)
if (sqd) {
mutex_unlock(&sqd->lock);
io_put_sq_data(sqd);
}
return ret;
}